Set your oven to 350°F (175°C) and line your baking sheets with parchment paper or a silicone mat.
Whisk together the flour, cocoa powder, baking soda, and salt in a medium bowl. Set aside.
Using an electric mixer, beat the softened butter and sugar until light and fluffy. This usually takes about 2-3 minutes. Add the egg and vanilla extract, then mix until well combined.
Gradually add the dry ingredients to the wet ingredients. Mix on low speed until a thick dough forms. Avoid overmixing to ensure tender cookies.
Wrap the dough in plastic wrap and refrigerate for at least 30 minutes. This step is essential to keep the cookies from spreading too much during baking.
Once chilled, scoop small portions of dough (around 1 tablespoon) and roll them into balls. Roll the dough balls in granulated sugar or sprinkles for an extra fun texture.
Place the cookie balls on your prepared baking sheet, leaving about 2 inches of space between them. Bake in the preheated oven for 10-12 minutes, or until slightly puffed.
Remove the cookies from the oven and allow them to cool on the baking sheet for 5 minutes before transferring them to a cooling rack.
That’s it! You’re just a few steps away from enjoying delicious homemade cookies.